Communication method, apparatus, and system

Abstract

Embodiments of this application provide a communication method, apparatus, and system, and provide an access procedure in which a device actively initiates access. The communication method includes: A first device sends configuration information to a second device, where the configuration information is used by the second device to determine a first time domain resource and/or a first frequency domain resource for sending a first message when the second device actively initiates access, and the first message is used by the second device to request to access the first device. When failing to receive the first message from the second device on the first time domain resource and/or the first frequency domain resource, the first device sends a second message to the second device, where the second message indicates the second device to access the first device again.

1 - 20 . (canceled) 
     
     
         21 . A method, the method comprising:
 sending, by a first device, configuration information to a second device,   wherein the configuration information is used by the second device to determine a first time domain resource or a first frequency domain resource for sending a first message when the second device actively initiates access, and the first message is used by the second device to request to access the first device; and   in response to failing to receive the first message from the second device on the first time domain resource or the first frequency domain resource, sending, by the first device, a second message to the second device,   wherein the second message indicates the second device to access the first device again.   
     
     
         22 . The method according to  claim 21 , wherein the second message comprises first indication information or the first time domain resource or the first frequency domain resource, wherein the first indication information, the first time domain resource, or the first frequency domain resource indicates, to the second device that fails to access the first device on the first time domain resource or fails to access the first device on the first frequency domain resource, to access the first device again. 
     
     
         23 . The method according to  claim 22 , wherein the second message is further used by the second device to determine a second time domain resource or a second frequency domain resource used to send a third message, and the third message is used by the second device to request to access the first device again. 
     
     
         24 . The method according to  claim 21 , the method further comprising:
 in response to successfully receiving the first message from the second device on the first time domain resource or the first frequency domain resource, sending, by the first device, second indication information to the second device,   wherein the second indication information indicates that the second device succeeds in the access.   
     
     
         25 . The method according to  claim 21 , wherein the first message comprises a random number, and the method further comprises:
 sending, by the first device, a fourth message to the second device,   wherein the fourth message comprises third indication information indicating to use two-step random access, or the fourth message comprises configuration information corresponding to the two-step random access.   
     
     
         26 . The method according to  claim 21 , wherein the first message comprises a preamble or a random number, and the method further comprises:
 sending, by the first device, a fifth message to the second device,   wherein the fifth message comprises fourth indication information indicating to use four-step random access, or the fifth message comprises configuration information corresponding to the four-step random access.   
     
     
         27 . A method, the method comprising:
 receiving, by a second device, configuration information from a first device,   wherein the second device uses the configuration information to determine a first time domain resource or a first frequency domain resource used to send a first message when the second device actively initiates access, and the second device uses the first message to request to access the first device;   in response to actively initiating the access, sending, by the second device, the first message to the first device on the first time domain resource or the first frequency domain resource; and   in response to the first device failing to receive the first message from the second device on the first time domain resource or the first frequency domain resource, receiving, by the second device, a second message from the first device,   wherein the second message indicates to the second device to access the first device again.   
     
     
         28 . The method according to  claim 27 , wherein the second message comprises first indication information or the first time domain resource or the first frequency domain resource,
 wherein the first indication information or the first time domain resource or the first frequency domain resource indicates, to the second device that fails to access the first device on the first time domain resource or the first frequency domain resource, to access the first device again.   
     
     
         29 . The method according to  claim 28 , wherein the second device further uses the second message to determine a second time domain resource for sending a third message, and the second device uses the third message to request to access the first device again. 
     
     
         30 . The method according to  claim 27 , the method further comprising:
 in response to the first device successfully receiving the first message from the second device on the first time domain resource or the first frequency domain resource, receiving, by the second device, second indication information from the first device,   wherein the second indication information indicates that the second device succeeds in the access.   
     
     
         31 . The method according to  claim 30 , wherein after receiving, by the second device, the second indication information from the first device, the method further comprises:
 changing, by the second device, first information from a first value to a second value,   wherein a value of the first information of a device that actively initiates access and that fails the access is the first value, and a value of the first information of a device that actively initiates access and succeeds in the access is the second value or a value of the first information of a device that does not actively initiate access is the second value.   
     
     
         32 . The method according to  claim 27 , wherein the first message comprises a random number, and the method further comprises:
 receiving, by the second device, a fourth message from the first device,   wherein the fourth message comprises third indication information indicating to use two-step random access, or   the fourth message comprises configuration information corresponding to the two-step random access.   
     
     
         33 . The method according to  claim 27 , wherein the first message comprises a preamble or a random number, and the method further comprises:
 receiving, by the second device, a fifth message from the first device,   wherein the fifth message comprises fourth indication information indicating to use four-step random access, or   the fifth message comprises configuration information corresponding to the four-step random access.   
     
     
         34 . A second device, comprising:
 at least one processor; and   at least one memory coupled to the at least one processor and having program instructions stored thereon that, when executed by the at least one processor, cause the second device to:
 receive configuration information from a first device, 
 wherein the second device uses the configuration information to determine a first time domain resource or a first frequency domain resource used in sending a first message when the second device actively initiates access, and the second device uses the first message to request to access the first device; 
 in response to actively initiating the access, send the first message to the first device on the first time domain resource or the first frequency domain resource; and 
 in response to the first device failing to receive the first message from the second device on the first time domain resource or the first frequency domain resource, receive a second message from the first device, 
 wherein the second message indicates to the second device to access the first device again. 
   
     
     
         35 . The second device according to  claim 34 , wherein the second message comprises first indication information or the first time domain resource or the first frequency domain resource,
 wherein the first indication information or the first time domain resource or the first frequency domain resource indicates, to the second device that fails to access the first device on the first time domain resource or the first frequency domain resource, to access the first device again.   
     
     
         36 . The second device according to  claim 35 , wherein the second device uses the second message to determine a second time domain resource to send a third message, and the second device uses the third message to request again to access the first device. 
     
     
         37 . The second device according to  claim 34 , wherein the program instructions further cause the second device to:
 receive second indication information from the first device,   wherein the second indication information indicates that the second device succeeds in the access.   
     
     
         38 . The second device according to  claim 37 , wherein the program instructions further cause the second device to:
 change first information from a first value to a second value,   wherein a value of the first information of a device that actively initiates access and that fails the access is the first value, and a value of the first information of a device that actively initiates access and succeeds in the access is the second value or a value of the first information of a device that does not actively initiate access is the second value.   
     
     
         39 . The second device according to  claim 34 , wherein the first message comprises a random number, and the program instructions further cause the second device to:
 receive a fourth message from the first device,   wherein the fourth message comprises third indication information indicating to use two-step random access, or   the fourth message comprises configuration information corresponding to the two-step random access.   
     
     
         40 . The second device according to  claim 34 , wherein the first message comprises a preamble or a random number, and the program instructions further cause the second device to:
 receive a fifth message from the first device,   wherein the fifth message comprises fourth indication information indicating to use four-step random access, or   the fifth message comprises configuration information corresponding to the four-step random access.